Lubricant



Patented Feb. 12, 1945 LUBRICANT Walter 'r. Watkins, In, Elizabeth, N.J., assignor to Standard Oil Development Company, a'cor poratlon ofDelaware No Drawing. Application December 20, 1940, Serial No. 370,961

12 Claims.

The present invention relates to improvements in lubricants andespecially to the improvement of lubricating oils principally useful forinternal combustion engines operating under severe conditions. Theinvention will be fully understood from the following description.

Lubricating oils which exhibit improved performances under all types ofoperating conditions when used for the lubrication of heavy dutygasolineengines and for Diesel engines are coming.

into greater and greater demand. The requirements for such. oils arebeing steadily made more stringent and it has been proposed to addvarious ingredients to these oils to improve-their behavior in suchservice. The main purpos of these ingredients is to bring about greaterengine cleanliness and to avoid ring sticking, varnish formation andcarbon deposition. Some of the materials proposed for this-service areexcellent in one or more respects but are'found to be unfavorable inother respects; for' example, some of the com,- pounding agents arefound to be corrosive to bearings, especially the newer type alloys ofsflver and cadmium and of copper and lead.

The addition agents which form the basis of the present invention arethe oil soluble salts of xanthie acids. These acids have the followinggeneral formula:

where H is a hydrogen atom replaceable by metal and where R is an alkylradical such as CrHs, CaH'l,

etc., or a higher radical of the same general type such as CuHzs orCmHsv, or a cycloalkyl or aralkyl radical such as cyclohexyl or benzyl.Also, these radicals may contain sulmtituent groups such as halogen,Sulfur, phosphorus, nitro, amino, hy-

droxyl, and the like.

One method of preparing these salts is by reacting carbon disulflde withthe alcohol corresponding to the particular radical R, in the presenceof a strong alkali such as caustic potash. The potassium salt thusformed can be reacted with a suitable inorganic salt to produce thedesired compound by double decomposition. Thus,

for example, nickel amyl xanthate was prepared method of preparing thesecompounds, the methods being given forthe purpose of example only. I

The metal salts of the xanthic acids-which are used in the presentinvention, comprise the class of the oil soluble salts of metals of the1st, 2nd, 3rd, 4th, 6th and 8th groups of the periodic table ofelements. In addition to metallic salts, the salts of other salt formingradicals ma be employed similarly. Thus, the xanthic acid salts ofammonia, of quaternary ammonium bases, of sulphonium and phosphoniumbases, of pyridine, amines and the like may be used. These various saltsare not strict equivalents, in the sense that some are particularlyuseful for certain operations and others for other conditions, but amongthe most important metals are lithium, sodium, potassium, aluminum,chromium, tin, the metals of the 2nd group, in particular zinc, calcium,barium, cadmium and magnesium, and the metals of the 8th group,particularly nickel and cobalt.

The alcohols from which the xanthic acid salts are prepared must be sochosen as to provide 'a final product possessed of the desired oilsolubility. While the nickel salts of even ethyl xanthic acid are fairlyoil soluble, xanthic acids prepared from higher alcohols are requiredfor the otherpreparations, as for instance, the calcium and bariumcompounds, if these are to possess adequate solubility in the base oil.Salts of xanthic acids prepared from suitable polyhydric alcohols arealso contemplated. Different oils exert different powers of solution butsolubility may also be improved by the inclusion of mutual solvents suchas chlorinated hydrocarbons, higher alcohols, higher acids, esters,phenols, and the like,

The above mentioned salts are added to the oil in proportion from about0.10 to 4 or 5%. If

desired, single metal salts of a single xanthic acid may be used, butsinglesalts of mixed acids,

prepared from mixed alcohols, are also contemplated. Furthermore, if itis desired, salts of mixed metals may be employed, for example,magnesium and barium or other metals of the groups listed above.

More broadly the compounds employed in the present invention may berepresented by the general formula:

R-O- -s-M-'r.

in which R is an alkyl, cycloalkyl or aralkyl nium, ammoniump'suifonium,and the like); T may also be RFO-C'(S)S or other group capable oflinking with M, such as: alcohol, thio- I alcohol, ,acid, phenol,thiophenol, phenolsulfide; and n is an integer whose value is chosen tosatisfy valence requirements. When M is monovalent, n is obviously 0.

Other examples of xanthate salts which may 7 be employed in thisinvention include the followorder to give the oils greater load carryingcapacity, or even extreme pressure properties, but the present compoundsare fairly efiective as load carrying agents and one of their particularvirtues is the fact that they are non-corrosive to the present bearingalloys as well as to copper, brass and the like. It is found desirable,however, in many cases to add small amounts of a higher alcohol orcarboxylic acid to these oils, particularly when they are employed forthe lubricaticn of Diesel engines. For this purpose,

xanthate, zinc cyclohexyl xanthate, cobalt amyl xanthate, calciumchlorocetyl xanthate, calcium benzyl xanthate, aluminum butyl xanthate,barium ethyl amyl xanthate and magnesiumcalcium decyl, xanthate. It isnot intended that the invention be limited to the compounds listed,which are given merely for the purpose of illustration.

The hydrocarbon oils used may be straightmineral lubricating oils ordistillates derived from paraffinic, naphthenic or mixed base crudes or,if desired, various blended oils may be employed as well as residuals,particularly those from which asphaltic constituents have been carefullyremoved. The oils may be refined by conventional methods using acid,alkali and/or clay, or they may be extracted oils produced, for example,by solvent extraction with solvents of thetype of phenol, sulfurdioxide, furfural and the like. Hydrogenated oils may be employed aswell as synthetic oils prepared, for example, by the condensation ofolefins or reaction of carbon oxides with hydrogen. The lubricatingoils, how'- ever they'may.have been produced, may vary considerably inviscosity and other'properties, depending on the particular use forwhich they are desired, but they usually range from about 40 to 150seconds Sabolt at 210 F. The oils may be free from other addition agentsor they may contain other materials for particular purposes. Forexample, thickeners such as polyisobutylene may be added, as well asesters, to increase oiliness. Sludge dispersing agents, dyes, pourdepressants and anti-oxidants may also be employed for their particularpurposes without departing from the present invention. Additional sulfuror chlorine containing compounds may be added in the amount of alcoholor acid may be less than about 1%. v

It has also been found desirable in some cases to add these metallicxanthates to lubricating oil blends containing other metallic additionagents such as metallicphenolates, metallic phenol sulfides, metallicalcoholates, metal soaps and the like, the metallic xanthate and theother metallic compound exerting mutual assistance in improving theperformance characteristics of the lubricating composition.

The following examples may be considered to illustrate the nature andthe effects of the present agents:

Example 1 To a sample of well refined lubricating oil, SAE 40 grade, wasadded /4% of a nickel salt of ethyl xanthic acid which has the followinformula:

This sample and also the oil which did not contain the nickel xanthatewere then run under identical and carefully controlled conditions in aC. l. R. engine for 14 hour periods while maintzgining the coolingjacket at a temperature of 3 0 F.

After each test the engine was taken down and the piston assembliescarefully examined. Each part, that is rings, grooves, Skirt and thelike, was rated according to its condition. From these separate ratingsan over-all rating was determined by a system of weighting the ratingsof the separate parts so as to take into account each factor. The dataon the two runs are given in the following table:

Rings stack 1 on Over Ring Ring Bkirt all slits grooves varnish No.Degrees SAE 40 oil........ 5. 20 3 810 7. 17 6. 5 6.0 Oil-+0.25% Ni.

ethyl xanthate- 1.48 0 0 1. 67 3.8 V 0.25

Example 2 A blend of 0.5% of nickel amyl xanthate was prepared in anaphthenic base lubricating oil having a viscosity of about 55 Sayboltseconds at 210 F. This oil blend was tested for 60 hours in aCaterpillar Diesel engine under high-temperature conditions (210 F. oil;F. atmosphere) and its erformance was compared with that of thenaphthenic oil alone under the same conditions and for the same lengthof time. After each test the various parts of the engine .were examinedand given demerit ratings. The data obtained are presented below. Itshould be borne in mind that the higher the figure given the worse thecondition observed. It will be seen-that the blend containing nickelamyl xanthate was deflnitely better than the naphthenic oil alone.

. Copper-lead on Overall Egg on mm bearing demerit demem demerit weightloss,

. grams Naphthenic oi1.. l. 91 2. 93 5. 0.014 Naphthenic oil Ni amylxanthate 1. 37 86 3. 00 0. 004

I claim:

where R is an alkyl radical of less than 20 carbon atoms.

- 4. Product according to claim 3 inwhich the metal salt is. a salt of ametal of the 8th group.

5. Product according to claim 3 in which the metal salt is a nickelsalt.

- 6. Product according to claim 3 in which the metal salt is nickel amylxanthate.

7. Product according to claim 3 in which the salt is a salt of a metalof the 2nd group.

8. Product according to claim 2 in which the metal salt is a calciumxanthate.

9. Product according to claim 2 .in which the metal salt is an aluminumxanthate.

'10. The method of cleansing and lubricating automotive engines whichconsists in charging to said engines a lubricant comprising a mineralhydrocarbon oil having incorporated therein a salt or an alkyl xanthicacid, the alkyl radical of which contains less than 20 carbon atoms, inamount and potency suflicient to obviate the formation ofvarnish andsludge deposits and to remove anysuch deposits already present.

1'1. Method of cleansing and lubricating engines according to claim 10in which the salt of a muthic acid is a nickel salt of an acid havingthe following formula:

where R. is an alkyl radical of less than 20 carbon nickel amylxanthate.

WALTER 'r. WATKINS, JR.

